4 ms·

In general or specific to Covid-19 vaccines, does anyone knows what happens if you get vaccinated after you got the virus?

ageitgey 6y ago
On one hand, all of these vaccine trials excluded people who already had COVID, so we don't fully know what the effect would be in large numbers. However at least one person with COVID immunity accidentally got into the Oxford Phase 1/2 trial (according to earlier published results), so we at least know it didn't hurt them. On the other hand, it is generally thought that vaccines can trigger immune reactions that are often much stronger and longer lasting than just being infected, so you would expect there to be a benefit to getting vaccinated even if you already had it. But only time will tell for sure. No one really knows how long immunity of either type will last - we just have to wait and find out!
- logicchains 6y ago
  >On the other hand, it is generally thought that vaccines can trigger immune reactions that are often much stronger and longer lasting than just being infected, so you would expect there to be a benefit to getting vaccinated even if you already had it. Interestingly the opposite is true for influenza: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870374/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870374/
puzzlingcaptcha 6y ago
I doubt it would help much, for similar reasons why you don't give a flu vaccine to someone already sick. A vaccine is meant to stimulate adaptive immunity which culminates in formation of memory cells - highly selected T and B lymphocytes which are very specific to the infectious agent. This process typically takes a couple days [1] and is rather involved. Once you have the memory cells, however, the next time you get in contact with the virus your memory cells will jump-start the immune response much more quickly, before the virus gets a chance to replicate. In a regular infection the same mechanisms of adaptive immunity are activated, but on top of that you already have the complications from the virus itself (cell death in lung epithelium, accumulation of excess fluid, hypoxia, cytokine storm etc). A vaccine dose won't necessarily speed it up, there are plenty of virus particles already stimulating the immune system - it's just picking up the slack a bit too late. There are other factors to consider but that's the general idea. [1] https://www.researchgate.net/figure/Kinetics-of-CD8-T-cell-differentiation-following-viral-infection-Shown-is-a-typical_fig6_258857348 https://www.researchgate.net/figure/Kinetics-of-CD8-T-cell-d...

ageitgey 6y ago

On one hand, all of these vaccine trials excluded people who already had COVID, so we don't fully know what the effect would be in large numbers. However at least one person with COVID immunity accidentally got into the Oxford Phase 1/2 trial (according to earlier published results), so we at least know it didn't hurt them. On the other hand, it is generally thought that vaccines can trigger immune reactions that are often much stronger and longer lasting than just being infected, so you would expect there to be a benefit to getting vaccinated even if you already had it. But only time will tell for sure. No one really knows how long immunity of either type will last - we just have to wait and find out!

logicchains 6y ago
>On the other hand, it is generally thought that vaccines can trigger immune reactions that are often much stronger and longer lasting than just being infected, so you would expect there to be a benefit to getting vaccinated even if you already had it. Interestingly the opposite is true for influenza: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870374/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870374/

puzzlingcaptcha 6y ago

I doubt it would help much, for similar reasons why you don't give a flu vaccine to someone already sick. A vaccine is meant to stimulate adaptive immunity which culminates in formation of memory cells - highly selected T and B lymphocytes which are very specific to the infectious agent. This process typically takes a couple days [1] and is rather involved. Once you have the memory cells, however, the next time you get in contact with the virus your memory cells will jump-start the immune response much more quickly, before the virus gets a chance to replicate. In a regular infection the same mechanisms of adaptive immunity are activated, but on top of that you already have the complications from the virus itself (cell death in lung epithelium, accumulation of excess fluid, hypoxia, cytokine storm etc). A vaccine dose won't necessarily speed it up, there are plenty of virus particles already stimulating the immune system - it's just picking up the slack a bit too late. There are other factors to consider but that's the general idea. [1] https://www.researchgate.net/figure/Kinetics-of-CD8-T-cell-differentiation-following-viral-infection-Shown-is-a-typical_fig6_258857348 https://www.researchgate.net/figure/Kinetics-of-CD8-T-cell-d...